At Ahmad bin Ali Stadium on Saturday, Argentina defeated Australia 2-1 thanks to goals from Messi and Julian Alvarez. A late scare came from an own goal by Enzo Fernandez.
Only Gabriel Batistuta (10) has scored more goals for La Albiceleste in World Cup competitions than Messi (9), and the captain applauded the travelling supporters' efforts as his team proceeded to play the Netherlands in the quarterfinals.
"I am very happy for taking another step forward and achieving another objective," Messi said at a post-match press conference. "[Australia] were very strong and it was a difficult match, we knew it would be this way.
"We played very recently and didn't have much time to rest up, so we were concerned as we knew it would be a very physical match. Luckily we found the goal, and then at two goals ahead it was easier for us.
"I am very happy to share these beautiful moments with all the fans, I know the efforts they have made to be here with us in every match. The whole of Argentina would like to be here."
Messi made his 169th appearance for Argentina, to go with 778 at Barcelona and 53 at Paris Saint-Germain. To date, he has 789 goals and 338 assists across those 1,000 games, and Australia were the 129th team he has scored against in his career.
"This bond or union that we have with the fans is something beautiful, and that's what the national team should be," Messi said.
"We were excited and eager to be together with the people again. It's unbelievable, the passion and energy they transmit."